The OTA update file for Galaxy Nexus is about 75MB in download and will show up as a notification on your smartphone.
You can also manually check for the update by going to Settings >> About Phone >> System Update >> Check Now.
The same process can be applied to Nexus 7 also.
As the update is rolled out in batches, it might even take some days for the update to reach your device, so be patient.
To remind you, Android 4.2 brings new photo sphere camera, gesture typing, multiple users support (only on tablets), enhanced Google Now, improved notifications, and lock-screen improvement.
If you have already updated your Galaxy Nexus or Nexus 7 to Android 4.2, how is the latest Jelly Bean update treating you, do let us know in comments.
